To study the conversion of aromatic nitrogen-containing pollutants into toxic hydroxamic acids in marine organisms. The biochemical pathway by which this process occurs has been previously elucidated by this investigator. This unique and abnormal biochemical conversion is based upon the reaction of aromatic nitroso compounds with cofactor intermediates of thiamine present in certain enzymes. These enzymes are universally distributed in living systems. Studies will continue to elucidate those chemical and biochemical processes by which nitrosoaromatics are produced in aquatic environments. Particular emphasis will be placed upon a recently discovered group of peroxidatic enzymes that convert arylamines to nitrosoaromatics. Nitrosoaromatic production by biochemical reduction of nitroaromatics will also be investigated. Both in vitro and in vivo studies will be conducted with representative marine organisms, primarily invertebrates. The chemicals to be employed are representative nitrogenous pollutants, one of which is a known carcinogen. Continuing studies will involve the use of unlabeled chemicals, with later studies employing 14C radiolabeled compounds. The fate of such labeled arylamines and nitroaromatics in selected marine organisms will be determined. This study will enable us to estimate the potential hazard of certain man-made pollutants both to the health of the marine environment and to human health. The potential human health problem is one of environmental carcinogenesis.